The objectives of this project are: (1) to identify, adapt or develop, and pretest simple methods of measuring the bacterial and chemical composition of dental plaque and saliva, (2) develop methods of assessing host resistance (3) to conduct short-term clinical studies of agents which might promote oral health. Recent in vitro studies have identified a reliable, clinically feasible method of determining the tissue loss and the surface extent of active incipient dental caries. Tissue porosity was determined by measuring the amount of fluorescein which could be extracted from the fluorescein treated lesion, and lesion extent was documented by fluorescence photography. Short-term clinical studies of CPS will begin when approved by the appropriate review boards. Testing of biochemical tests are being conducted as collaborative efforts within the section and with other groups within the NIDR.